Question

Find the values of p and q such that (x+1) and (x-1) are the factors of x^4+px^3+2x^2-3x+q

Answer 1

if x+1 is a factor p(-1)=0

ie 1-p+2+3+q=0

-p+q=-6......[1]

if x-1 is a factor p(1)=0

ie 1+p+2-3+q=0

p+q=0......[2]

[1]+[2]    -p+q+p+q=-6

q=-3

substituting in [2]

p=3